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  • 09 Criminal Offences and Penalties
  • Traffic Offences
  • Random Breath Testing (RBT)
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Random Breath Testing (RBT)

The introduction of random breath testing (RBT) in 1985, expanded the powers of the police to require motorists to undergo breath tests. Any person driving a motor vehicle on a public street, or occupying the driver’s seat and attempting to drive the vehicle, can be required to undergo a breath test. A police officer may request or signal the driver of any vehicle to stop for the purpose of administering the breath test.

The device used for roadside testing is called an alcometer. The driver is asked to blow into this device, and an electronic light indicates whether the driver’s breath contains alcohol above the prescribed limit. Failure to pass the roadside test cannot by itself lead to conviction for drink driving. If the test is positive, the police officer may detain the driver and take them to a police station, or some other place where a further test can be conducted on portable breath analysing equipment known as a breathalyser (see below).

Random breath testing is carried out by pairs or teams of police officers using a breathalyser. Motorists are stopped at random and given a breath test. If the breath test proves positive, a breath analysis is conducted on the spot.


‘Driving’ under the Act does not only mean being behind the wheel of a car in motion. It has been given an extended statutory meaning to allow police greater powers to catch drink drivers (s2(4)Road Safety (Alcohol & Drugs) Act). Therefore a person may still be regarded as driving even though they have stopped the car, and got out.

In June 1988 Tasmanian police introduced a computerised alcotester (breathalyser), regarded as the most accurate and advanced in Australia. The driver blows into a mouthpiece and the machine makes a printout of the blood alcohol concentration level. A copy of the printout is given to the driver.

In Tasmania, any driver with 0.05 g of alcohol (or above) in 100 millilitres of blood, will be liable to conviction for this offence. The police officer’s certificate containing the blood alcohol reading is admissible in court as proof that the person was driving with a blood alcohol level in excess of the prescribed limit (s23Road Safety (Alcohol & Drugs) Act).


Penalties are provided under the Road Safety (Alcohol & Drugs) Act 1970, section 17 indicating the minimum and maximum Penalty Units, periods of disqualification and periods of imprisonment are doubled for second offences.

If a person satisfies the court that there are special circumstances why the minimum fine or minimum period of disqualification should not be imposed, the court may impose a lesser fine or a lesser period of disqualification (s17(5)). In some instances job loss and financial hardship for both the offender and their family will not be special circumstances within the meaning of section 17(5). Strong evidence establishing no possibility of alternative employment may be sufficient. However, this is a matter to be examined according to the facts of each case.

Limits on Breath Tests

Evidence of a blood alcohol concentration is not admissible if the breath analysis or blood test was taken in excess of 3 hours after the relevant act of driving (s24). In certain circumstances, a medical practitioner may refuse to allow testing of a driver who has become hospitalised or is in the doctor’s care (s12).

A police officer can require a person who is not at that time driving a motor vehicle to undergo a breath test if he or she believes on reasonable grounds:

  • that the person was immediately preceding that time driving on a public street with alcohol in their blood;
  • that the offence of causing death by dangerous driving has been committed;
  • that the vehicle driven by that person has been involved in an accident.

Refusing a Breath Test

Any person who refuses to take a roadside breath test commits an offence and is liable to a fine of $500 to $3,000 and up to 12 months imprisonment (s17). If a person refuses to undergo a breath analysis test, a further offence is committed, and the person is liable to a similar penalty for a first offence or, in the case of second or subsequent offences, a fine of $1,000 to $6,000 and up to 24 months imprisonment.

It is a defence for the driver to show that they were unable on medical grounds at the time to undergo the tests. It is also an offence for a driver to do anything to alter their blood alcohol level between the time the driver is stopped by the police and the time that a roadside breath test or a breath analysis test is taken. The driver will be liable to the same penalty as for refusing to undergo a breath analysis test (s14).

Blood Tests

A person who is required to undergo a breath analysis test may immediately afterwards request that a blood sample be taken by a medical practitioner for analysis. The person must be made aware of that option. However, it is important to note that the driver must still have undergone the breath analysis test, and will commit an offence by refusing. Where a blood sample is taken it must be divided into three parts, one of which is to be handed to the person, one to the Government Analyst and one retained as a control. A person has a right to have their portion independently analysed.

Unless the person is given the opportunity to analyse the sample themselves in this way it cannot be used as evidence against them. It is not commonly an advantage to have a blood sample taken in preference to a breathalyser test, as readings are usually higher, and will be used as evidence in preference to a breathalyser result if applicable. However, if the person has not consumed alcohol for at least one hour prior to driving, their blood sample may show a lower reading because of the time that has elapsed between the breathalyser test and the taking of the blood sample. Where a blood sample is taken from a person when unconscious, that person should be informed within 24 hours that a sample has been taken.

Insurance and Exceeding 0.05

Most insurance policies covering damage to motor vehicles contain a provision excluding the liability of the insurer if the driver was under the influence of intoxicating liquor at the time of an accident. The fact that a person has submitted to a breath test or breath analysis, or has been convicted of exceeding 0.05 offence, cannot by itself be used by the insurer to exclude liability (s21).

However, insurance companies can avoid liability to indemnify an insured, if they can show the driver was under the influence of alcohol by evidence other than a blood alcohol reading.

Page last updated 09/03/2021

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